Causes Of Failure With A Connecting Rod

A connecting rod is a crucial part of the engine, connecting the piston to the crank. In collaboration with the crankshaft, it converts the reciprocating motion to rotation motion or the vice. Today, the rod gets used with internal piston engines examples of the automobile engines.

The Connecting rods if not properly taken care of can result in engine damage. But what causes the rods’ failure remains a mystery to many. In consideration to this, we present you with a list of possible causes of connecting rod failures and their possible prevention techniques. These include;

1. Overloading the Rods

Usually, the rods are strong enough to accommodate extreme performance modifications. They also can handle some of the racing types. However, they have the limits to which they can comfortably handle. With an increase in power levels and RPMs, the rods will get the point where they cannot support the job further.


And this can lead to the connecting rod failure which in return can get the engine destroyed within a second. Overloading associates with extreme racing where the motor makes higher horsepower than needed. However, cases of rod failure about overloading are not common.

2. Less Lubrication and Heat

When there is a reduced gap between the rod’s bearing and the crankshaft surface, it minimizes the amount of film oil space. As a result, there is an increase in friction which in return generates more heat. The heat makes the bearing to expand resulting into reduction of oil delivery.

As the temperature increases to the peak, it results in annealing of the bearing towards journal race. And this tightens and freezes the bearings against crankshaft journal. To note the overheating, blue-black marks forms on the journals and the bearing. And this results to rod’s failure.

3. Elongated Rod Bore

In case the rod’s bore elongates more with high RPM, it can distort clearances that exist between the bearings and the shaft. It can also happen in case the bolts do not get properly torqued. If the bolt torque doesn’t get proper fixing, it fails to keep the rod in place.


The bolts can also be very weak at high RPMs. Such property will pull the cap away off the connecting rod. When the rod is not in its correct positioning, it results to rod’s failure which in return will destroy your car’s engine.

4. Bolt Stretch

When we experience tight bearing, it can result in excessive bolt stretch. The final result is tearing and weakening of available threads in rod cap. When the rod bolts get exposed to such stress, they weaken, and their tensile power gets reduced.

As a result, such bolts cannot get reused, and if they do will not show the expected torque numbers. To handle the case, we recommend that you use bolt stretch gauges in measuring bolts’ length when they are fully torqued and loaded to their specifications.

Preventing Connecting Rod Failure

When it comes to preventing connecting rod failure, you can adopt different strategies. First, make use of the aftermarket rod bolts. These bolts are stronger and have a double tensile strength in comparison to stock rod bolts. Also, they have a wide range of applications.


Second, consider upgrading your rods on a regular basis. By doing this, you replace the worn out rods to prevent rod failure that could result in engine failure.

In conclusion, the above are among some of the causes of rod failure. Consider identifying each case and learn how it can get prevented. By doing this, you reduce the chances of destroying your engine.